A novel dieless bellows forming process using local heating technique

In this work, we present a finite element analysis and experimental study of the metal bellows manufacturing using dieless forming technique. Currently metal bellows Is fabricated by using tube hydro or air-pressure forming followed by upsetting process. However, these methods are not efficient and suitable especially for small quantity production and various workpiece sizes. Therefore, the dieless metal processing is applied in order to overcome these problems. It is found that the deformation characteristics of metal bellow such as convolution height and pitch distance Is affected by compression ratio (C= v₁/ v₂). At low compression ratio, thickening of the tube wall thickness occurred. While the higher compression ratio produces a convolution. The convolution height also depends on compression ratio. The convolution height Increases with Increasing compression ratio up to a critical value. Over the critical compression ratio, convolution height keeps a constant. The convolution pitch is affected by tube thickness. Thinner tube has tendency to produce irregular convolution pitch due to high sensitivity of buckling. It can be concluded that metal bellows can be fabricated by using dieless compression technique successfully. The finite element analysis shows good agreement with experimental results.